Thanks for the photo, but the are beaucoup
picture of the masts available. I was looking for a reference that showed which mast was what. The snorkel is easy-- the fat one at the rear. The two "AN/" arrays are probably antennas, so I'll pick one that fits best. The two "Type 18 or 8 " masts are optical periscopes, but since this is a modern boat I'll assume that the video-photonics head is used in preference to the optical scopes, and it must be the remaining (unnamed) mast.
The thin styrene masts will be breakage-prone, so I can make them out of .070" carbon fiber rod and mold the mast fairings from epoxy lightened up with microbeads. I did a quick weigh and the new limited number of masts weigh no more than the six stock plastic ones, so it's good from a balance standpoint.
Onto the next hurdle...